Significant advances have been made in recent years in development of vascular prosthesis. For example, U.S. Pat. No. 4,131,604 to Szycher entitled Polyurethane Elastomer for Heart Assist Devices discloses a family of polyurethanes with excellent properties which can be used to form moldable prosthetic devices. However, one deficiency of the polyurethane disclosed in that patent is that the polyurethanes are not extrudable. There are many prosthetic devices as well as other devices, which can only be manufactured efficiently by extrusion or blow molding, which must be blood compatible.
It should be apparent that devices such as pacemaker leads, blood bags, catheters, and I.V. tubing must be formed of a material that meets a number of criteria. The most significant criteria is that the material from which such devices are fabricated must be non-toxic and hemocompatible. That is, the material does not induce the formation of a thrombus which can embolize into the distal bloodstream. In addition to the foregoing, it is desirable that materials for devices to be used in manufacturing vascular prothesis possess a high degree of resiliency, strength and an ability to flex without breakage. As is mentioned above for the formation of certain devices, it is desirable that the material be extrudable.